We have been performing a clinical study using CMX-001, a lipid-conjugated form of cidofovir, which has excellent oral bioavailability and lacks the kidney toxicity of cidofovir, in patients with severe herpes simplex, cytomegalovirus, and adenovirus infections. In addition to using CMX-001 for these diseases, we also treated an immunocompromised patient who had disseminated molluscum contagiosum virus (MCV) disease and severe human papillomavirus with CMX-001. While the patient had to stop the medication due to toxicity, we found that she had MCV DNA in 20% of blood samples while on therapy, compared with MCV DNA in 50% of blood samples while off of therapy. We noted improvement of her human papillomavirus infection of her fingers while on CMX-001. This study suggests that CMX-001 may be beneficial in immunocompromised patients with certain severe virus infections. We have also been searching for new viruses in persons with unexplained diseases. We studied cohorts of patients with chronic fatigue syndrome and chronic inflammatory diseases of unknown etiology (including rheumatoid arthritis, Behcets disease, systemic lupus erythematosis, dermatomyositis, polymyositis, and scleroderma) for evidence of xenotropic murine leukemia virus-related virus (XMRV) and other murine leukemia virus-related viruses. Prior reports had shown an association of these viruses in patients with chronic fatigue syndrome. We failed to convincingly detect virus sequences in patients with chronic fatigue syndrome, chronic inflammatory syndromes, or in blood bank donors. Serum from patients with chronic fatigue syndrome did not contain antibodies to XMRV. Thus, we did not detect evidence of XMRV infection in patients with chronic fatigue syndrome or in those with chronic inflammatory diseases whose cause is unknown.